Chaeles selden



(No Model.)

O. SELDEN.

TELEGRAPH RECEIVER.

PatentedMay 1, 1 888.

amm coz who 131M243 UNITED STATES PATENT ()FFICE.

CHARLES snLDEr oF BALTIMORE, MARYLAND.

TELEG RAPH -RECEIVERQ SPECIFICATION forming part of Letters Patent No. 382,195, dated May 1, 1888. Application filed November 15, 1887. Serial No. 255.247. (No model.)

To all whom it may concern:

-Be it known that I, CHARLES SELDEN, a citizen of the United States, and a resident of the city of Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Telegraph-Receivers, of which the following is a specification.

My invention relates to tone or harmonic telegraphy, and more particularly to the manner of receiving the tones or signals adapted for use in such systems; and it has for its object to so improve such systems and provide such receiving-instruments that a large number of separate messages may be transmitted and received upon a single wire without interference with each other and without danger of disturbance from induction or other causes; and my invention consists more particularly in the receiving-instruments constructed and arranged substantially as hereinafter described, and in the application and adaptation of such instruments for various kinds of telegraphy. It is Well understood in this class of telegraphy that a series of transmitters are suitably connected and arranged to throw or superpose upon the main line independent series of impulses varying in rate or number for each transmitter, and

I have not deemed it necessary to show or describe any particular form of transmitter in this case, as my present invention relates more particularly to the receiving apparatus.

I am aware that many forms of receivinginstruments have been proposed for separating and receiving the different series of impulses or variations of potential on the line and transforming them into audible or other signals, so that they can readily be understood by the receiving-operator; and I am also aware that the use of tuning-forks or equivalent instruments have been proposed, which forks have been tuned to vibrate at some certain rate corresponding with the number of impulses sent upon the line bythe particular transmitter to which the tuned fork is intended to respond.

In the present instanceI make use of a tun ing-fork, and preferably one that is permanently magnetized; and I operate this tuningfork so as to produce vibrations in the, ends of the tines thereof electrically by means of a magnet or other device connected in the main distances;

line. It is well known that a tuning fork tuned, for instance, to vibrate at a rate of three hundred and sixty vibrations a second will respond not only to impulses at that rate, but also at any rate which is about an exact divider of the former-that is to say, that a tuning-fork the fundamental tone of which is three hundred and sixty vibrations will also respond to one hundred and eighty, ninety, sixty,or even forty-five vibrations to the second. It is equally well knownthat a transmitter giving forty-five impulses only, or any other number than the fundamental tone of the tuning-fork,will not act as efficiently thereon and produce vibrations in the tuning-fork of as great an amplitude as a transmitter giv' ing the fundamental number of vibrations, or three hundred and sixty pulsations persec ond;

' but still the influence of the transmitter producing forty-five, sixty, or ninety vibrations is sufficiently great to produce more or less motion in the tines of the fork, which is liable to cause false signals or to break up the true signals, especially when transmitting over long These effects have been found to be of great importance in the use of the tuning-fork as a receiver in tone or harmonic 'tele graphs, especially when it is desired to send a large number of messages over a single wire,

and various efforts have been made to over come these objections; and one of the features of my invention consists in providing means for overcoming these objections, and in the ap* plication of such means to operate various forms of receiving-instruments, the practical operation of which depends upon the accurate operation of the primary receiver.

In order to more clearly illustrate my in vention, reference is made to the accompanying drawings, in which Figure 1 represents an embodiment of my invention, the drawing being partially in section. Fig. 2 is a diagrammatic representation showing the effects of the various rates of vibration of the tines of the fork upon the receiver. Fig. 3 is a diagrammatic representa tion showing the receiver connected with an ordinary differential sounder. Fig. i is a similar diagram showing the application of the receiver to an automatic or fac-simile telegraph. Fig. 5 is a similar diagram. Fig. 6

have a certain fundamental rate of vibrationfor instance, three hundred and sixty vibrations a second-corresponding with the impulses produced by the particular transmitter connected in the main line to which it is adapted to respond.

Upon a suitable base, S, is mounted asta-ndard, P, which is made so as to be adjustable longitudinally in the base by means of the adj usting-screw E. Mounted in the standard P, but insulated therefrom, is a rod, B, upon one end of which is placed a coiled spring,.b, the other end being preferably bent at right angles and carrying an adj llSlillJg-SOIQW, D,which forms one of the contact-points, and which normally rests in contact with the point 0, fixed in the pillar, the contact being maintained by the spring b. Suitable binding-posts are attached to the pillar and to the rod B, as indicated.

This apparatus is shown connected for operation in the diagram, Fig. 3, of the drawings, in which L B is a local battery, H a differential sounder, and M the armature thereof. Normally the contact-points O D are in contactand included in one branch of the local circuit surrounding the differential magnet of the sounder, and the armature is unaffected by the magnet. When, however, the tuningfork A is operated by means of the impulses over the main line L, one of the tines, F, vibrates sufficiently to impinge upon the end of the rod B and to break the contact between the points 0 D, when the equilibrium of the differential magnet is disturbed, and the armatureM'is attracted and operates to produce the proper signal.

It will be understood that the vibrations of the tines of the tuning-fork are comparatively rapid, and while the tendencyofi the spring b is to close the contact between the points 0 D immediately after the impact of the tine or arm F against the rod B is broken the action of the spring is not sufficiently rapid to com-' pletely close the contacts and to establish .the V circuitof the local battery throu ghthose points, so as to disturb the balance of the magnetsufficiently to releasethe armature; or it may be that the core of the magnet is of such material and proportion as to have a eomparatively sluggish action, so that if perchance the contacts OD do actually impinge the momentary current that might flow through that branch of the local circuit is not sufficient to demagnetize the magnet of the sounder and disturbthe armature, and the result is that as long as the tuning-fork is vibrating at the proper rate of speed the armature is held down to make the signal, and as soon as the fork stops the contact-points are operated to complete the balance of the magnet and to release the armature. Such is the operation of the tuning fork and receiver when the proper number of impulses are being transmitted over the main line L to produce the fundamental tone of the tuning-fork A. As before stated, however, other rates of impulses have more or less effect upon the tuning-fork, as, for instance, one hundred and eighty vibrations, or half of the fundamental tone; or it has been found that even if the number ofvibrations is three hundred and fifty perhaps,or some other damental tone of the fork, the result of the influence of these varying rates of vibrations is to produce false signals. I It is understood, however, that the full effect or vibration of the arms of the tuning-fork will not be produced unless the normal or fundamental num- Fig. 2' I have illustrated, on an exaggerated der these varying influences. When the proper rate of vibrations or impulses is sent over the line corresponding to the fundamental tone of the fork, the tines will vibrate to the extent shown by the heavy dotted lines 00 x, and the result will be that one of the tines will impinge upon the rod B and break the contact between G and D of the receiving-instrument as the tines then vibrate to their full amplitude; but when impulses of other rates are rethe tines F F" will not be so great and will only have an amplitude indicated by the dotted lines y y, and by means of the adjustments in under these conditions. Another important feature results from this mode of adjusting the receiving-instrument. It is well known that induction, which may result from various causes, has an influence upon the receivinginstrument and produces vibrations to a greater or less extent in the receiving-fork; but as these vibrations are not those corresponding to the fundamental of the tuningfork the rod B can be adjusted over these vibrations, so that the contact-points will not be affected and the disturbing influences will not be liable to produce false signals.

From the above the importance of my invention will be readily understood, as it will be seen that the instrument can be so delicately adjusted that the receiver will not respond to vibrations unless the proper rate is being transmitted and affects the fork so as. to produce the full amplitude of its vibrations,

gle line over which are sent varying series of number very nearly approximating the fun-' ber of impulses are transmitted to it, and in ceived which affect the fork the vibration of my receiving device the rod B is so arranged that the contact-points O D willnot be afiected I and it therefore results that a large number of receiving-instruments may be placed in a sin-:

scale, the position of the tines of the fork un- 9 5 throughout the whole time impulses and each receiver will only respond to its predetermined number of impulses and will not be affected by induction and other disturbing causes.

This receiver may be applied not only to a sounder, differential or otherwise, as shown in Fig. 3,'but is specially applicable to an automatic or autographic receiver, as illustrated in Fig. 4, in which the cylinder 0 or other device carrying, for instance, a chemicallyprepared paper, is connected in one branch of the local circuit with a point or style, as Q, resting thereon, and the contact-points CD are so arranged as to normally short-circuit the local battery LB. When, however, the fork is vibrated to its fullest extent, its arm or tine F impinges upon the rod B and breaks the local circuit at the contact-points O D, and the current from the local battery is caused to flow through the cylinder or plate 0 and its superposed paper or other receiving device, and the current passing through the same causes arecord to be produced in the welle known way. In place of using the chemically-prepared paper,as indicated in Fig. 4, it is evident that the armature M, as shown in Fig. 3, may be provided with a pin or pencil, p, which may be brought to bear upon a strip of paper or other material, g, which may be caused to travel in a well-known way underneath said pin whenever the contact at the points 0 D is broken and the balance of the differential magnet is disturbed.

When the apparatus is used in making facsimile or other records, it is desirable that the point or style Q should remain in absolute contact with the chemically-prepared paper that the signal is being transmitted, and as I have found for the reasons before stated that sometimes the circuit at the contact-points O Dmay be momentarily established, so that the result would be that the signal produced on the traveling paper would be broken or even in the form of continuous dots or dashes instead of a continuous line; and in order to remedy this and to enable me to produce a perfect facsimile I employ an arrangement whereby the circuit may be momentarily broken at the point-s O D, and still the record would be made as a continuous line, and this is illustrated in Fig. 5, in which the contact-points O D are included in a branch of the local battery L B, which branch forms the primary R of an induction-coil, the secondary T of which includes a second stylus, U, which is arranged in close proximity to the first stylus, Q, on the paper, and the operation will be readily understood to be that should there be makes or breaks at the contact-points in the circuit when the primary pulsations begin or cease I the secondary currents set up by such action in the coil '1 would pass through the stylus U and supplement the dots or dashes made by the style Q, so as to fill the interstices or spaces between them and produce a continuous line,

and thus by the use of thetwo styluses, one connected in the primary and the other in the secondary thereof, a record-line that is con tinuous will be produced.

While I have thus described the construction of my device, so that contacts 0 D are normally closed, it is evident that it may be constructed and arranged so that the contacts would be normally open and the contact completed by the vibrations of the tuning-fork, and this is illustrated in Fig. 7, in which like parts are lettered as in the formerfigures, and which require no specific construction.

A modified form of my invention is illustrated in Fig. 6, in which the tuning-fork is provided with an extension, m, secured, for instance, upon one side of the arm or tine F, while upon the other side of the same arm, but insulated therefrom, is secured a bent spring-arm, a, each of which arms are included inthe local circuit L, and the contact is normally completed at the points 0 d, while suitably supported in relation thereto is the screw K, which is so adjusted that when the fork is vibrated to its full amplitude the extension of the springa impinges upon the end of the screw K, breaking the local circuitat the contact-points c d, producing the results above described in any receiving-instrument connected in the local circuit.

It will thus be seen that the principle of my invention may be embodied in various forms of devices by those skilled in the art, and I therefore do not wish to limit myinvention to the precise construction and arrangement shown in the drawings.

What I claim is- 1. In a tone or harmonic telegraph, the combination, with a tuning-fork operated by the main current, of an independent set of contacts in a local circuit, a support for the contacts and adjusting devices for said substantially as described.

2. In a tone or harmonic telegraph, the combination, with a tuning-fork operated by the main current, of asupport carryinga fixed contact-piece, a movable contact-piece also mountsupport,

IIO

ed in the support, a local circuit including the contacts,and adj usting screws for the contacts, substantially as described.

3. In a tone or harmonic telegraph, the combination, with a tuning-fork operated by the main-line current, of an independent set of adjustable contacts included in a local circuit, and a signal-receiving instrument cuit, substantially as described.

4. In a tone or harmonic telegraph, the combination, with a tuning-fork and an independent set of contacts operated thereby, of a local in the circircuit including thecontacts in one branch,

and .an automatic receiving-instrument in an other branch, substantially as described.

5. In a tone or harmonic telegraph, the combination of a tuning-fork operated by the mainline currents, a set of contacts in a local circuit operated by the fork, an automatic re- 10 tacts may be arranged so as to be operated only when the fork vibrates normally, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of twosubscribing witnesses.

CHARLES SELDEN.

\Vitncsses:

N. O. GRIsWoLD, EDGAR W. DAY. 

